Continuous conveyor belts to transport products between work stations have been extensively used since the industrial revolution. The construction of these continuous conveyor belts is well known. In their simplest form, conventional conveyor belts include a drive roller which is coupled to some energizing force such as an electric motor, or the like, and which further rotates the drive roller in a given direction. Spaced a given distance from the drive roller is an idler roller. The continuous conveyor belt is tensioned between the drive roller, and the idler roller. Rotation of the drive roller imparts motion to the conveyor belt which then travels and moves about the idler roller and then returns to the drive roller. The upper facing surface or top flight of the conveyor belt generally supports a product or objects that need to be transported along the upper facing surface or top flight of the conveyor belt.
At relatively low operational speeds, the continuous conveyor belt typically rotates and stays oriented along a given path of travel between the drive roller, and idler roller during operation. However, as rotational speeds and conveyor belt speeds have increased, it has long been recognized that continuous conveyor belts can migrate, “creep” or otherwise move laterally or from side-to-side toward one peripheral edge and away from the opposing peripheral edge. This lateral or side-to-side movement increases the wear on the conveyor belt because of increased friction. Often this side-to-side migration or “creeping” is caused by numerous factors including bearing wear which causes the respective axles supporting the drive roller, and the idler roller, to become misaligned or otherwise located in a non-parallel relationship thus causing or encouraging the conveyor belt to migrate to one side or the other of the respective rollers. In other instances, the mere wear of the conveyor belt due to its continuous usage with a given product causes the conveyor belt to wear un-evenly and thus migration results. Still, in other instances, the high speed of rotation of the conveyor belt may cause the belt to unduly vibrate during operation. This vibration motion, again, encourages migration of the conveyor belt in one direction, or another. Yet further, and while the drive roller, and idler roller may be maintained in a substantially parallel relationship, a non-horizontal orientation of the conveyor assembly, as a whole, can encourage migration or “creeping” of the rotating conveyor belt in one direction or another. Yet further still, uneven loading of the conveyor belt, where more quantity, or weight, of product is placed on one portion of the belt offset from a centerline can cause the belt to migrate laterally toward one edge and away from the other.
Once this lateral or side-to-side motion of the conveyor belt is observed, adjustments can be made to either the drive roller or idler roller, or both, so as to encourage the continuous conveyor belt to move back to an appropriate orientation relative to the rollers and into a proper predetermined course of travel. Such an adjustment to the drive roller or idler roller, or both, is normally done by hand, and requires some degree of expertise, in order to effect the appropriate adjustment which is necessary to cause the continuous conveyor belt to move back to an appropriate orientation relative to the drive and idler rollers, respectively. For particularly long and continuous conveyor belts, this adjustment process may take some period of time, and may further, on occasion, cause the conveyor assembly to be taken out of service while the adjustments are being made. Obviously, the failure to make the appropriate adjustments to the drive or idler rollers may result in a premature wearing of the conveyor belt, or perhaps even a catastrophic failure of the conveyor belt and entire conveyor assembly, depending upon the type of conveyor belt being employed.
An optical sensor based system to monitor and automatically adjust the position of a continuously rotatable conveyor belt is described in co-pending U.S. application Ser. No. 14/848,717, filed on Sep. 9, 2015. The entire contents and teachings described in U.S. Ser. No. 14/848,717 are hereby expressly incorporated herein.
The optical sensor based system is founded on the physics of known distance, and a known speed of electromagnetic waves, both of which may be used to calculate a known time for the electromagnetic waves to travel the known distance using the formula d=vt (where “d” represents distance; “v” represents velocity and “t” represents time). Optical sensor based systems have proven effective but are dependent upon contrasts in colors and are sensitive to debris and product splatter which are common in high-speed, high-volume, automated sorting applications. Shielding and screens, and the like have been employed to protect the sensors and to maintain contrasts, but even such shielding/screens can, over time, develop deposits of splatter, debris, dirt, water and the like which can negatively affect the accuracy of the optical systems by diminishing contrasts as well as partially or completely blocking transmission and receipt of the electromagnetic waves.
Use of waves to determine measurements and distances and to provide data for making adjustments remains a valuable tool. A “wave” is defined in the McGraw-Hill Dictionary of Scientific and Technical Terms (Fifth Ed., 1994). Wave: “a disturbance which propagates from one point in a medium to other points without giving the medium as a whole any permanent displacement.” Further, the term “Wave Motion” is defined in the same text as: “The process by which a disturbance at one point is propagated to another point more remote from the source with no net transport of the material of the medium itself; examples include the motion of electromagnetic waves, soundwaves, hydrodynamic waves in liquids and vibration waves in solids”.
It has been found by the inventors herein that mechanical waves provide an accurate means of measuring, tracking and providing data so as to facilitate adjustments to a continuously rotatable conveyor belt without the drawbacks inherent in optical sensor based systems that are reliant upon electromagnetic waves.
An apparatus for adjustably positioning an object of interest such as a rotating conveyor belt is the subject matter of the present Application.